Early modern humans living on the southern Africa coast employed pyrotechnology, the controlled use of fire, 72,000 years ago, to increase the quality and efficiency of their stone tool manufacturing process, according to a report in Science.

The international team of researchers deduces that "this technology required a novel association between fire, its heat, and a structural change in stone with consequent flaking benefits." Further, they say their findings ignite the notion of complex cognition in early man.

If their findings hold up, it could mean humans' ability to solve complex problems may have occurred at the same time their modern genetic lineage appeared, rather than developing later as has been widely speculated.

The South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project (SACP4) at Pinnacle Point, Mossel Bay, is under the direction of Curtis Marean, a paleoanthropologist with the Institute of Human Origins and a professor in the School of Human Evolution and Social Change at Arizona State University. Credit: Image by Erich C. Fisher/Arizona State University/ South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project (SACP4)

"Our illumination of the heat treatment process shows that these early modern humans commanded fire in a nuanced and sophisticated manner," says lead author Kyle Brown, a doctoral candidate at the University of Cape Town, and field and lab director in Mossel Bay, South Africa, for ASU's Institute of Human Origins. "We show that early modern humans at 72,000 years ago, and perhaps as early as 164,000 years ago in coastal South Africa, were using carefully controlled hearths in a complex process to heat stone and change its properties, the process known as heat treatment."

"Heat treatment technology begins with a genius moment – someone discovers that heating stone makes it easier to flake," says Curtis Marean, project director and a co-author on the paper. Marean is a paleoanthropologist with the Institute of Human Origins and a professor in the School of Human Evolution and Social Change at Arizona State University's College of Liberal Arts and Sciences. "This knowledge is then passed on, and in a way unique to humans, the technology is slowly ratcheted up in complexity as the control of the heating process, cooling and flaking grows in sophistication."

This creates a long-chain technological process that the researchers explain requires a complex cognition, and probably language, to learn and teach.

Barbecuing Rocks

The heating transformed a stone called silcrete, which was rather poor for tool making, into an outstanding raw material that allowed the modern humans to make highly advanced tools. The focus of Brown's research involves experimentally replicating the types of tools and production debris found at African archaeological sites to understand how and why people made and used these tools.

"In numerous field surveys with co-author David Roberts, who is a leading expert on silcrete formation, we were unable to locate stone outcrops with material that matched the fine-grained texture and often reddish color of the silcrete artifacts we excavated at Pinnacle Point," Brown says. "The silcrete we had collected was just not suitable for tool production."

Most of the silcrete they found was intensively flaked. It was unusual to find a piece larger than a few centimeters. However, one day in 2007, while Brown and Marean were at the Pinnacle Point Site 5-6 (PP5-6) they found a huge flake of silcrete embedded in ash – the largest piece of silcrete they had ever seen on an archaeological site, nearly 10 centimeters in diameter.

"It looked like it had been accidentally lost in a fire pit," Brown notes. He recalls how many of the silcrete tools from the site had a sheen or gloss that reminded him of tools he had examined in North American collections that were heat-treated.

Stratigraphic layers visible in this lower section of the PP5-6 archaeological site of the South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project (SACP4) site at Pinnacle Point, Mossel Bay, date to 79,000 to 86,000 years ago. The site is where an international team of researchers discovered evidence that early modern humans employed pyrotechnology to increase the quality and efficiency of their stone tool manufacturing process. Credit: Photo by Simen Oestmo/South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project (SACP4)

"That is when we developed the heat treatment idea," Marean says. "The co-association of the ash cemented to the silcrete, the red color of the silcrete, and its inexplicably large size was the genesis conditions of our eureka moment."

To test their theory, Brown placed some of the silcrete stone beneath their fire pit one evening, building a hot fire over the top.

"When I returned to dig the stone out the following day, the results were amazing. After heating, the silcrete became a deep red color and was easily flaked. Most importantly, it looked exactly like silcrete from site PP5-6. Using heated silcrete we were then able to produce realistic copies of the actual silcrete tools," Brown says.

"Here are the beginnings of fire and engineering, the origins of pyrotechnology, and the bridge to more recent ceramic and metal technology," Brown says.

According to Marean, the silcrete bifaces are re-usable tools with many potential functions: effective hunting weapons, excellent knives and items of value for exchange.

"This explains why people would invest so much effort at wood collection and heat treatment for their production," Marean says.

Early humans living on the southern coast of Africa 72,000 years ago may have used a complex heat treatment process to manufacture blades and bifacial tools. Unheated silcrete (left) can show dramatic changes in color and texture after heating and flaking (right). The researchers note that silcrete is not found closer than 5 kilometers from their excavation at Pinnacle Point, Mossel Bay, South Africa, and that most pieces found are extensively flaked. Credit: Photo by Kyle Brown/South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project (SACP4)

And, the hearths used to test their theory "were designed to mimic what people in the past may have done. So, not only did we heat silcrete, but we barbecued (a 'braai' in South Africa) steaks and chops at the same time as measuring the temperature profiles with our thermocouple," Marean says.

Symbolic behavior and modern human origins

"Our discovery shows that these early modern humans had this complex cognition," Brown says.

"This expression of cognitive complexity in technology by these early modern humans on the south coast of South Africa provides further evidence that this locality may have been the origin location for the lineage that leads to all modern humans, which appeared between 100,000 and 200,000 years ago in Africa," explains Marean.

"There is no consensus as to when modern human behavior appears, but by 70,000 years ago there is good evidence for symbolic behavior," he says. "Many researchers are looking for technological proxies for complex cognition, and heat treatment is likely one such proxy.

"Prior to our work, heat treatment was widely regarded as first occurring in Europe at about 25,000 years ago," Marean says. "We push this back at least 45,000 years, and, perhaps, 139,000 years, and place it on the southern tip of Africa at Pinnacle Point."

The African location was at the center of another discovery by Marean – the documentation of the earliest evidence for exploitation of marine foods and modification of pigments – reported in the Oct. 17, 2007, journal Nature.

"Combined, these results sharply advance our knowledge of modern human origins, and show that something special in human cognition was happening on the coastline of South Africa during this crucial final phase in human origins," Marean says.

He adds that some time around 50,000 to 60,000 years ago, "these modern humans left the warm confines of Africa and penetrated into the colder glacial environment of Europe and Asia, where they encountered Neanderthals.

"By 35,000 years ago these Neanderthal populations were mostly extinct, and modern humans dominated the land from Spain to China to Australia," Marean says.

"The command of fire, documented by our study of heat treatment, provides us with a potential explanation for the rapid migration of these Africans across glacial Eurasia – they were masters of fire and heat and stone, a crucial advantage as these tropical people penetrated the cold lands of the Neanderthal," says Marean.

Other members of the research team and co-authors of "Fire As an Engineering tool of Early Modern Humans," include David Baun, University of Cape Town; Andy I.R. Herries, University of New South Wales and University of Liverpool; Zenobia Jacobs and Michael C. Meyer, University of Wollongong, Australia; Changal Tribolo, CNRS-University of Bordeaux, France; David L. Roberts, Council for Geoscience, Republic of South Africa; and Jocelyn Bernatchez, Institute of Human Origins, ASU.

They work together on the South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project, known as SACP4, which is directed by Marean, funded by the National Science Foundation and the Hyde Family Foundation, and supported by Arizona State University research and academic units including the Institute of Human Origins, Institute for Social Science Research, and School of Human Evolution and Social Change in the College of Liberal Arts and Sciences.

"Our team, working at Pinnacle Point near Mossel Bay, is a leader in revealing the process of how we became who we are today, and we are doing this with state-of-the-art fieldwork and laboratory analysis at this locality," Marean says.

Comments

These advances seem to represent the limits of native Africans. Cognitive evolution, for all intents and purposes, appears to have ceased there soon afterwards. Further advances had to await the advent of Europeans and Asians.

It looks like those answers need to be discovered. Who knows what other realities lie buried? Take an Anthropology class. No human race was really limited. Humans adapt to their environment based on their surroundings and the hardships they face, humans will develop tools and methods to survive. Because many of the tools and artifacts may have been made out of material that decays more quickly than others over time, we may never know the full story. Thank God our ancestors were very good travelers. I can't wait to see what else history has for us to discover about our past.

It's folly to assume advances ceased in one region as well. Science has really gotten some people up in arms when it's discoveries challenge people's prejudices. I love science. Evolution of humans did have a set pattern; science is pretty damn predictable. The key to evolution is time. The same amount of time passed, regardless of whatever region our ancestors migrated into. Overtime, they evolved into what we know as modern man today. These early humans, regardless of region, had to face some of the same basic challenges: Food, shelter, and protection. Based on the environment (location, temperature, and available resources), humans came up with ideas about how to survive. Whatever it was, it worked. The point of this article is that humans from very early on developed tools to survive. It wouldn't make any sense that they would have been able to spread into other areas of Africa or the rest of the world if they really couldn't survive where they were. This article gives our human ancestors more credit than people generally like to. We are all the same people. We are from the same source. No one has developed into a different species. When we have a different species that develops let me know. Otherwise, we are still the same. It might be painful for you to believe, but we are one group of people. Pretty soon the idea of race will be obsolete; we will all be so mixed up it won't matter. Happy thought.

I woke up this morning to the shock of my life. My teacher was actually right! I read this and printed this out to show him when I start school in 2 weeks. He said at some point archaeologists will find evidence that early humans were more intelligent than previously thought.
"Our discovery shows that these early modern humans had this complex cognition," Brown says.
This is absolutely amazing.

Aww, Steve it's okay. Embrace unity. Based on your posts, I took you for a person who didn't like diversity. I can't wait until we all are so mixed up no one can really try and make themselves feel good by making someone else look bad. If it is so unnatural, then why is it happening?

It's happening because it's the official ideology, promoted 24/7/365 by media, public and private education and every level of government. It's surprising how little mixing actually goes on in spite of all this.

Racial/ethnic groups still demonstrate a very strong inclination towards self-segregation, despite the propaganda tsunami pushing the contrary. For example, you'll have the devil's own time convincing East Asians to "mix it up."

I believe in diversity. Groups should be allowed to maintain their identities, lifestyles and traditions. If they want their own physical enclaves, I'm fine with that, too.

The Aussies are into silcrete studies in a big way. This online blogoid SILCRETE With special reference to the Sydney region is full of interesting stuff about it, including the fact that the "sarsen" stones used in building Stonehenge and Averbury (cue: Land of Hope and Glory) are composed of it.

For Aboriginal Australians, it appears to have been the material of choice for perhaps tens of thousands of year, though my web scouring suggests that they upgraded the technology in what for us would still be the dim and distant past, and tended to move over to quartzite.

The Aussies have been aware of heat treatment of silcrete for some time, and there is an interesting paper recommending the use of multiple experimental techniques (particularly microscopy and palaeomagnetism) to tell whether the heat was applied before or after the flaking.

Steve, not everything has to be about race; it obviously weighs heavily on your mind. No one is forcing anyone to intermarry; media generally reflects reality. The point of this article is to demonstrate that early humans were intelligent and did have the ability to think and create.

Really, it is a two-way street with the media. I would ask Steve to give me examples of the media promoting interracial relationships 24/7/365, but that would distract further away from the point of this article.